A display element taking advantage of a guest/host effect achieved by adding a dichroic dye to liquid crystals has attracted public attention as a display element suitable for a medium to large-scale display, since it has the following advantages:
(1) Having a wide angle of view; PA1 (2) Capable of readily realizing a colorful display by selecting dyes; and PA1 (3) Not always requiring a polarizing plate and thus capable of giving a clear display.
Conventional display elements taking advantage of a guest/host effect achieved by adding a dichroic dye to liquid crystals can hardly satisfy a high stability at a low temperature, a high contrast, high lightshielding properties, a long lifetime and various hues at the same time. A contrast ratio is expressed in the ratio of the volume of light at the transmission to that at the shade. In order to achieve a high contrast ratio, therefore, it is required not only to give a high dichroic ratio of the dye but also to lower the volume of transmitted light corresponding to the denominator, namely, elevating the solubility of the dichroic dye. When different types of dyes are blended together, however, an irregularity is sometimes observed in the solubility of each dye component in the blending system and that observed when each dye is used alone. That is to say, the solubilities in the blending system frequently fail to achieve an additive property. When different types of dyes are blended together, furthermore, the photo-deterioration of some of these dyes is frequently accelerated. As a result, it becomes difficult to simultaneoulsy satisfy a high stability at a low temperature, a high contrast, high light insulating properties and a long lifetime in the cases of, in particular, practically valuable colors such as black or dark blue.
In order to overcome these problems, JP-A-62-064887 has disclosed a liquid crystal composition comprising specific dichroic dyes of three types and a display element using the same.
It is an object of the present invention to provide a color liquid crystal composition which is excellent in stability at a low temperature, contrast and light-resistance and superior, in particular, in contrast and light-shieding properties to the one disclosed in JP-A-62-064887 as well as a display element to thereby solve the abovementioned problems such as the irregularity in solubilities and photodeterioration.